Author(s): Li, ZQ (Li, Ziqi); Peng, B (Peng, Bo); Lin, ML (Lin, Miao-Ling); Leng, YC (Leng, Yu-Chen); Zhang, B (Zhang, Bin); Pang, C (Pang, Chi); Tan, PH (Tan, Ping-Heng); Monserrat, B (Monserrat, Bartomeu); Chen, F (Chen, Feng)

Source: NPJ 2D MATERIALS AND APPLICATIONS Volume: 5 Issue: 1 Article Number: 87 DOI: 10.1038/s41699-021-00268-3 Published: NOV 26 2021

Abstract: Information technology demands high-speed optoelectronic devices, but going beyond the one terahertz (THz) barrier is challenging due to the difficulties associated with generating, detecting, and processing high-frequency signals. Here, we show that femtosecond-laser-driven phonons can be utilized to coherently manipulate the excitonic properties of semiconductors at THz frequencies. The precise control of the pump and subsequent time-delayed broadband probe pulses enables the simultaneous generation and detection processes of both periodic lattice vibrations and their couplings with electronic states. Combining ultralow frequency Raman spectroscopy with first-principles calculations, we identify the unique phonon mode-selective and probe-energy dependent features of electron-phonon interactions in layered PdSe2. Two distinctive types of coherent phonon excitations could couple preferentially to different types of electronic excitations: the intralayer (4.3 THz) mode to carriers and the interlayer (0.35 THz) mode to excitons. This work provides new insights to understand the excited-state phonon interactions of 2D materials and to achieve future applications of optoelectronic devices operating at THz frequencies.

Accession Number: WOS:000722860600001

eISSN: 2397-7132

Full Text: https://www.nature.com/articles/s41699-021-00268-3